JPH0868313A - Control device for diesel particulate filter - Google Patents

Abstract

PURPOSE: To improve durability of a control device of a diesel particulate filter by accurately detecting an accumulation ratio of the particulates captured by the filter, and precisely controlling a regeneration timing of the filter, for increasing usage frequency of the filter. CONSTITUTION: A main filter 1 and a sub-filter 2 are arranged on an exhaust gas passage 22. An opening/closing valve 5 is arranged on the main filter 1, while a bypass valve 9 is arranged on the sub-filter 2. A controller 10 executes controlling of operating the opening/closing valve 5 and the bypass valve 9 in respect to detection signals of an particulate accumulation sensor 8 and a temperature sensor 29, carrying current to a wire gauge 6 composing a heater, and burning the particulates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a diesel particulate filter that collects exhaust gas discharged from a diesel engine by a filter and heats and incinerates it.

[0002]

2. Description of the Related Art Combustion of a diesel engine is based on so-called heterogeneous mixing, in which fuel is injected into high temperature, high pressure air. Unlike the homogeneous mixture, the heterogeneous mixture does not mix the air and the fuel uniformly, so the carbon components in the fuel change to soot, HC, etc. due to the high temperature heat of combustion, and they aggregate to form particulates. It is released to the outside and pollutes the surrounding environment. Conventionally, as an exhaust gas treatment device for treating exhaust gas of an engine, a diesel particulate filter using a porous filter has a large particulate collection area of the filter, and particulates are accumulated and collected on the filter. To be done. In order to incinerate the accumulated particulates, a heater is attached to the surface of the filter, and when the amount of particulates accumulated exceeds a specified standard, an electric current is passed through the heater to incinerate the particulates and regenerate the filter. There is.

Conventionally, Japanese Patent Application Laid-Open No. 2-256812 discloses an electrically regenerable particulate trap. The particulate trap comprises a gas permeable support, a fiber layer composed of a plurality of ceramic fibers, and a heater, the fiber layer is arranged together with the heater in a space extending in the radial direction from the gas permeable support, and the gap between the fiber layers is provided. The exhaust gas is caused to flow to collect the particulates in the exhaust gas in the vicinity of the heater, and the heater is energized to incinerate the collected particulates. The ceramic fiber is selected from continuous fused silica, glass, alumina silica, zirconia silica, alumina chromia, titania, graphite, silicon carbide, and alumina boria silica. Further, the ceramic fibers are braided or wound directly onto the gas permeable support or heater.

[0004]

By the way, since the diesel particulate filter is mounted on a vehicle or the like,
Construct as compact as possible, carbon, soot, HC
It is necessary to manufacture so that the collection of particulates etc. becomes efficient. Particulates react with oxygen and burn easily, but a high temperature is required for burning, and it is not possible to burn completely with the exhaust gas temperature alone. A conventional renewable diesel particulate filter has two filters of the same size arranged in parallel in the exhaust gas flow, and when one filter becomes clogged by the collection of particulates, the other filter is made to flow exhaust gas,
Air required for incineration of particulates is sent to the clogged filter to heat the filter, and the collected particulates are incinerated to regenerate the filter.

However, when the accumulated amount of particulates collected on the filter exceeds a predetermined amount, the heater is energized to heat, but a method for accurately detecting the accumulated amount of particulates on the filter is as follows. Very difficult. For example, in the conventional detection of the accumulated amount of particulates, a pressure sensor is provided on the filter upstream side of the exhaust gas flow, and the indirect method of measuring the exhaust gas pressure is used. It is difficult to accurately detect the amount of accumulation because it changes variously depending on the load of the engine, the number of revolutions, etc. For example, the exhaust gas pressure loss at full load and the exhaust gas pressure loss at partial load are different as shown in FIG. 7 because the flow rate changes because the exhaust gas temperature is different.
Further, the allowable value of the exhaust gas pressure loss P of the filter when the engine speed is high N ₂ and the increasing rate of the exhaust gas pressure loss P of the filter when the engine speed is low N ₁ are different. Even if the filter is clogged and cannot be used yet, if the filter is used at a low speed and a low load, the filter will continue to be used without being regenerated. Then, if the engine is suddenly operated at a high load, the exhaust gas pressure rises sharply, and the filter is loaded with a high exhaust gas pressure, and cannot withstand the high pressure.

Therefore, carbon, soot, HC to the filter
The ability to detect the accumulated amount of particulates as an absolute value is the most reliable control of the filter regeneration time, and is necessary to improve the durability of the filter. There was a problem of detecting the quantity as an absolute value.

Therefore, an object of the present invention is to solve the above problems, and a main filter for collecting particulates such as carbon, soot, HC contained in exhaust gas discharged from a diesel engine. In addition to being provided in the exhaust gas passage, a sub filter is provided in the main filter, an opening / closing valve is provided in the main filter passage and the sub filter passage, and a particulate deposition sensor is arranged on the upstream side of the exhaust gas flow of the main filter and the main filter is provided. It is an object of the present invention to provide a control device for a diesel particulate filter, which is provided with a temperature sensor and which regenerates the main filter in response to the detected values to keep the main filter clean at all times.

[0008]

In order to achieve the above object, the present invention is constructed as follows. That is, the present invention is a diesel particulate filter installed in an exhaust gas passage of a diesel engine, comprising a main filter having a large trapping capacity of particulates and a sub filter having a small trapping capacity, and the main filter and the sub filter. Each valve that opens and closes a passage with the filter, a heater for incinerating the particulates collected in the main filter and the sub-filter, and a particulate that detects the amount of particulates deposited on the main filter. The present invention relates to a diesel particulate filter control device comprising a deposition sensor and a controller that controls the valves and the heater in response to a detection signal from the particulate deposition sensor.

Alternatively, the present invention is directed to a main filter arranged in an exhaust gas passage of a diesel engine, a sub filter arranged in a bypass passage in the main filter, an opening / closing valve for opening / closing the main exhaust gas passage, and a bypass passage opening / closing. A bypass valve, a heater arranged on the surface of the main filter,
A heater disposed on the surface of the sub-filter, a particulate deposition sensor provided with a detection filter installed in the exhaust gas passage on the exhaust gas upstream side of the filter body, a temperature sensor for detecting the temperature of the main filter,
And a controller that controls the on-off valve, the bypass valve, and the heater in response to detection signals from the particulate deposition sensor and the temperature sensor to heat and incinerate the collected particulates. The present invention relates to a control device for a diesel particulate filter.

In this diesel particulate filter control device, the particulate deposition sensor comprises a detection filter having substantially the same ventilation resistance per unit volume as the main filter, and a conductive metal attached to both ends of the detection filter. And a resistance detector for measuring the resistance value between the terminals.

Further, in this diesel particulate filter control device, when the temperature of the main filter is high, the regeneration of the main filter is performed even if the particulate deposition amount of the particulate deposition sensor is below a predetermined amount. Is what starts. Further, when the temperature of the main filter is low, the regeneration of the main filter is started only when the particulate deposition amount of the particulate deposition sensor becomes a predetermined amount or more.

[0012]

The control device for the diesel particulate filter according to the present invention is constructed as described above and operates as follows. That is, the control device for the diesel particulate filter includes a main filter and a sub-filter arranged in an exhaust gas passage of a diesel engine, an opening / closing valve for opening and closing those passages, a heater arranged on the surface of the main filter, and a controller. The heating heater in response to a detection signal from a particulate deposition sensor having a detection filter installed in the exhaust gas passage on the exhaust gas upstream side of the filter body and a temperature sensor detecting the temperature of the main filter. Since the energization is controlled, the main filter can always be kept in a clean and optimum state. Further, it is possible to detect the deposition amount of the particulates trapped in the filter body by directly detecting the deposition amount of the particulates deposited on the detection filter, and the deposition amount on the filter body can be accurately measured. In addition, it can be detected quickly, and the time of regeneration of the filter body can be accurately controlled.

That is, the conditions for screening the main filter are that the higher the temperature of the entire filter is, the less electric energy is applied to the heating heater, and the amount of particulates deposited on the filter can be accurately detected. The ability to heat and incinerate particulates well, to reliably incinerate particulates deposited on the filter in a short time to increase the frequency of use of the main filter, and the particulate matter deposited on the filter under any operating condition of the engine. That is, the curate can be reliably heated and incinerated. Considering these conditions, at the time of regeneration of the main filter, when the filter temperature is higher than a predetermined value, the main filter becomes clogged with particulates and the resistance value becomes large. Thought to be an opportunity. Therefore, when the temperature of the main filter is high, the regeneration of the main filter is started by starting the regeneration of the main filter even in a state in which the amount of accumulated particulate matter of the particulate matter accumulation sensor is equal to or less than a predetermined withstand voltage considering durability. Control the filter so that it is played back in a short time. Further, when the temperature of the main filter is low, since it is at the time of partial load, the regeneration time is extended to the limit where the particulate deposition amount of the particulate deposition sensor becomes a predetermined amount or more, and the main filter Control to start playback.

In this diesel particulate filter control device, since the exhaust gas flows in parallel to the filter body and the detection filter, the amount of particulates trapped by the filter body and the detection filter are detected. The amount of particulates collected by the filter is equivalent to the unit area. Therefore, when particulates such as carbon, soot, HC, etc. are deposited on the detection filter in the particulate deposition sensor, carbon is deposited in the gaps of the detection filter, and the electrically conductive state is improved. The resistance detector can detect that the electric resistance value of the detection filter has become small, and the amount of particulate accumulation can be detected. When a certain amount of particulates is deposited on the detection filter, since a certain amount of particulates is also deposited on the filter body, the heating heater provided in the filter body is energized to heat and incinerate the deposited particulates, While the filter body is regenerated, the detection filter is energized to regenerate the detection filter at the same time.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a diesel particulate filter control device according to the present invention will be described below with reference to the drawings. 1 is a sectional view showing an embodiment of a control device for a diesel particulate filter according to the present invention, FIG. 2 is a plan view showing an example of a detection filter in the particulate accumulation sensor of FIG. 1, and FIG. FIG. 4 is a cross-sectional view showing another example of the detection filter in the curate deposition sensor, FIG. 4 is a plan view showing a wire net which constitutes a heater in the particulate deposition sensor of FIG.
5 and 6 are cross-sectional views showing an embodiment of the wire rod of the wire mesh.

This diesel particulate filter is arranged in the exhaust system of a diesel engine and can collect particulates such as carbon, soot and smoke contained in the exhaust gas, and heat and incinerate the collected particulates. And a case 21 connected to an exhaust pipe (not shown) of a diesel engine via a flange 23.
have. In the exhaust gas passage 22 formed in the case 21, the main filter 1 and the sub-filter 2 capable of collecting particulates are separated by the bypass cylinder 4 in the exhaust gas flow direction and are concentrically formed into the exhaust gas flow. They are arranged in parallel so as to extend from the inlet side to the outlet side. Further, the main filter 1 is composed of an inner cylinder 19 and an outer cylinder 20 which are cylindrical bodies which are concentrically and in parallel with each other in an exhaust gas flow and which are doubly stacked. Further, a heat shield layer 38 for heat shield can be formed on the inner wall surface of the case 21.

Except for the inlets 15 and 16 of the main filter 1 and the sub-filter 2 and the outlets 17 and 18 of the main filter 1 and the sub-filter 2, on the exhaust gas inlet side and the exhaust gas outlet side of the exhaust gas passage 22. In order to block the inlet side and the outlet side of the exhaust gas passage 22, a shield plate 24 is provided. A slidable tubular open / close valve 5 for opening / closing the main exhaust gas passage 12 is arranged on the upstream side of the exhaust gas inflow of the main filter 1, and the open / close valve 5 is opened / closed by an actuator 36 driven by a command from the controller 10. To be done.
The support pipe 13 is provided on the exhaust gas inflow side of the sub filter 2.
A bypass valve 9 for opening and closing the inlet of the sub-filter 2 is arranged in the support pipe 13.
The bypass valve 9 is opened and closed by an actuator 11 driven by a command from the controller 10. The opening / closing valve 5 and the bypass valve 9 may be provided with a through hole through which a small amount of exhaust gas leaks for the purpose of regenerating the main filter 1 and the sub-filter 2, and the opening / closing valve 5 and the bypass valve 9 themselves may leak. The exhaust gas passage 22 and the bypass passage 14 may be arranged so as to do so.

In this diesel particulate filter, in particular, the main filter 1 and the sub-filter 2 are composed of the filter body 3, and the wire mesh 6 made of a conductive material on at least the exhaust gas inflow side with respect to the inner and outer surfaces of the filter body 3. ，
7 are arranged. The filter body 3 is a plate-shaped and cylindrically-shaped member formed by laminating a long-fiber ceramic material obtained by adding an additive such as Ti or Ta to SiC or SiC. When the exhaust gas is passed through the filter body 3, the particulates in the exhaust gas are collected in the region where the fibers intersect with each other and are sequentially deposited between the fibers to increase the exhaust gas pressure on the upstream side of the filter body 3. It will be.

The metal nets 6 and 7 are provided with the metal net 6 on the upstream side of the exhaust gas flow of the main filter 1 and the metal net 7 on the downstream side of the exhaust gas flow of the main filter 1. Wire net 6,7
Is made of corrosion-resistant heat-resistant steel containing Ni, Cr, Al, etc., and can be fixed to the main filter 1 by arranging it on the surface of the filter body 3 and appropriately locking it with a stapler or the like. Main filter 1 is an inner cylinder 1 which is two cylindrical filters
9 and the outer cylinder 20, a main exhaust gas inflow passage 12 on the exhaust gas inflow side through which the exhaust gas flows is formed between the inner cylinder 19 and the outer cylinder 20, and the inner cylinder 19 and the outer cylinder 20 are formed. A main exhaust gas outflow passage 35 on the exhaust gas outflow side, through which the exhaust gas passing through the main filter 1 flows out, is formed on the outside of 20. For example, the outer cylinder 20 will be described. The wire nets 6 and 7 are fixed to the inner and outer surfaces of the outer cylinder 20 with a stapler or the like. At this time, the metal net 6 arranged on the inner surface of the outer cylinder 20, that is, on the exhaust gas inflow side.
Is made of a conductive material, and the terminal 30 is provided so that it can function as a heater. The wire net 7 arranged on the outer surface of the outer cylinder 20, that is, on the exhaust gas outflow side does not necessarily have to be made of a conductive material. In any case,
The metal nets 6 and 7 have a function of holding the filter body 3.

The wire mesh 6 is provided in the controller 1 in order to heat and burn the particulates collected in the main filter 1.
The energization is controlled by the command of 0. Although not shown, the sub-filter 2 may be provided with a wire mesh like the main filter 1 to heat and burn the particulates collected by the sub-filter 2. The wire nets 6 and 7 extend over the entire inflow upstream side of the main filter 1 of the exhaust gas passage 22 and the entire inflow upstream side of the sub filter 2 of the bypass passage 14, and are connected to the controller 10 through the electrode terminals 30. . Also, wire mesh 6
Is preferably made of a Ni-based metal and is configured so that the surface of the main filter 1 can be heated uniformly. The wire material that constitutes the wire net 6 is, for example, as shown in FIG.
3, the core member 31 made of a Ni—Cr alloy, the intermediate member 32 made of a material having a large temperature coefficient of resistance such as Ni coated on the core member 31, and the intermediate member 3
2 is coated with a corrosion-resistant Al ₂ O ₃ or ZrO ₂ coating layer 33.

The control device for the diesel particulate filter is that the particulate accumulation sensor 8 is provided on the inlet side of the exhaust gas passage 22. As shown in FIG. 2 or 3, the particulate deposition sensor 8 includes a detection filter 25 and a detection filter 25 that have substantially the same ventilation resistance per unit volume as the filter body 3.
Controller 1 for measuring the resistance value between terminals 26 and 26, which are made of conductive metal and are attached to both ends of
It is composed of a resistance detector (not shown) provided at 0. As shown in FIG. 2, the detection filter 25 is formed by laminating ceramics porous material in which SiC or an additive such as Ti or Ta is added to SiC, and Cu, Cr, A metal such as Ni is impregnated. Alternatively, the detection filter 25 may be the same as in FIG.
As shown in, SiC or Ti or T contained in SiC
It is formed by laminating a ceramic long fiber laminated material 25F containing a and a ceramic porous material 25P.
The detection filter 25 is a porous ceramic material 25P that is conductive or non-conductive, and has a characteristic that the porous body is clogged with carbon and particulates to be in a conductive state and the electric resistance value becomes small. In addition, Cu, Cr, and Ni are formed at the joint ends of the detection filter 25 so that the particulate matter accumulated between these filters 25 conducts between the terminals 26 and 26 to reduce the resistance value.
It is configured to be electrically impregnated with such a metal as described above, and to electrically connect the detection filter 25 and the connector of the terminal 26 favorably. On the other hand, on the surface of the detection filter 25, a wire net 34 made of heat-resistant steel that can be energized is arranged. As shown in FIG. It has been cut into. The cut portion of the wire net 34 is clogged with carbon and particulates to reduce the electric resistance. Depending on the case, the detection filter 25 may be made of conductive SiC fiber and terminals 26 are joined to both ends thereof, and in this case, it is not necessary to provide a wire mesh.

Information on the amount of deposition detected by the particulate deposition sensor 8 is input to the controller 10. Further, the controller 10 is provided with a rotation sensor 27 for detecting the engine operating state, that is, the engine speed, a load sensor 28 for detecting the engine load, and a temperature sensor 29 for detecting the exhaust gas temperature. The controller 10 receives these detection signals of the engine operating state, determines the particulate collection state corresponding to the detection value of the particulate accumulation amount that is predetermined corresponding to the engine operating state,
The opening timing of the on-off valve 5 and the bypass valve 9, that is, the regeneration timing of the main filter 1 is controlled.

Next, the operation of the control device for the diesel particulate filter will be described with reference to the control flow chart of FIG. The diesel engine is driven and the exhaust gas is sent to the exhaust gas passage 22 through the exhaust pipe. At this time, the opening / closing valve 5 is opened and the bypass valve 9 is closed. Exhaust gas is sent from the inlet 15 of the exhaust gas passage 22 to the main exhaust gas passage 12, passes through the main exhaust gas passage 12 through the main filter 1, and the soot, carbon, smoke, etc. contained in the exhaust gas at the main filter 1 The particulates are collected and clean exhaust gas is discharged to the outlet 17. The collected particulates will be deposited on the main filter 1, and the air passage resistance of the main filter 1 will gradually increase according to the collection time. on the other hand,
Similarly, the exhaust gas also flows through the particulate deposition sensor 8, and the particulate matter in the exhaust gas is collected by the detection filter 25. The controller 10 receives the detection signals from the particulate deposition sensor 8 and the temperature sensor 29, and determines the particulate deposition amount on the main filter 1 from the detected values.

In order to detect the amount of particulates deposited on the detection filter 25, the detection filter 25 is energized to detect the resistance value R _X of the detection filter 25, and the detected value is sent to the controller 10 to send it to the controller 10. Resistance value R
Whether _X is lower than a preset resistance value R ₁ (R ₁ > R
_X ) is determined (step 40). Resistance value R detected
_{If X} is higher than the set resistance value R ₁ , the main filter 1
Since there is not much particulate deposited on the sheet, the resistance of the main filter 1 is still high, and the regeneration of the main filter 1 is unnecessary, so the process returns to the beginning. When the detected resistance value R _X is lower than the set resistance value R ₁ ,
Since the state in which the particulates are trapped in the main filter 1 is shown to some extent, the controller 10 determines whether or not the temperature T _X of the main filter ₁ is higher than a preset temperature T ₁ (step 41).

When the temperature T _X of the main filter 1 is lower than the preset temperature T ₁ , a large amount of electric power is applied to the wire net 6 of the heater to heat the particulates collected in the main filter 1. Therefore, the regeneration process of the main filter 1 is not performed, and the particulates are continuously collected in the main filter 1 until the accumulated amount of the particulates on the main filter 1 reaches the limit. . Therefore, it is judged whether or not the resistance value R _X of the detection filter 25 is smaller than a preset limit resistance value R ₂ (step 42), and the resistance value R _X is smaller than a preset limit resistance value R _2. In this case, since the amount of particulates reaching the limit has been collected in the main filter 1, the process proceeds to the regeneration process of the main filter 1 and when the resistance value R _X is larger than the preset limit resistance value R _2. Is a state in which the amount of particulates up to the limit value is not collected in the main filter 1. Therefore, the process is performed by collecting the particulates by the main filter 1 without performing the regeneration process of the main filter 1. Return to 41. The resistance value of the main filter 1 is inversely proportional to the amount of particulate accumulation.

When the main filter 1 is regenerated while the temperature T _X of the main filter 1 is high, a surplus heater is used to heat and incinerate the particulates collected in the main filter 1. Since it is possible to regenerate the main filter 1 in a short time without supplying electric power to the wire mesh 6, the regeneration of the main filter 1 is immediately started. Also, the main filter 1
Even when the temperature T _X of the main filter 1 is low, the resistance value R _{X of the} main filter 1
Is less than the preset limit resistance value R ₂ ,
Since the particulates are trapped in the main filter 1 to the limit, the main filter 1 is regenerated also in this case.

First, in accordance with a command from the controller 10, the actuator 11 is operated to open the bypass valve 9 (step 43), and the actuator 36 is also operated.
Is operated to close the on-off valve 5 to close the main exhaust gas passage (step 44). When the bypass valve 9 is opened, most of the exhaust gas passes through the bypass passage 14 and the sub filter 2, and a small amount of the exhaust gas is sent from the exhaust gas passage 22 to the main filter 1. Further, the controller 10 issues a command to pass a current through the wire net 6 through the electrode terminal 30, the wire net 6 is heated, and the main filter 1 is heated (step 45). Here, the temperature T _X of the main filter 1 is measured by the temperature sensor 29, and the controller 1 determines whether the temperature T _X is higher than a preset temperature T _2.
The judgment is 0 (step 46). If the detected temperature T _X is lower than the set temperature T ₂ , it means that the particulates collected are not completely burned by heating. Therefore, the process returns to step 45 and the wire mesh 6 of the heater is continuously energized. To heat.

When the detected temperature T _X becomes higher than the set temperature T ₂ , the particulates of the main filter 1 are heated and burned well, so that state is maintained for a predetermined time (step 47). When the main filter 1 is heated, the particulates collected in the main filter 1 are converted to CO ₂ and H ₂ O by using the air contained in a small amount of exhaust gas passing through the main filter 1 and incinerated. Then, it becomes gas and is discharged from the outlet 17, and the regeneration of the main filter 1 is completed.
After the regeneration process of the main filter 1 has passed for a predetermined time, the power supply to the wire net 6 provided in the main filter 1 is stopped (step 48). At this time, the completion of regeneration of the main filter 1 is determined by the controller 10 based on the incineration time with respect to the accumulated amount of particulates in consideration of the engine operating state.

On the other hand, in the exhaust gas passing through the sub-filter 2, the particulates contained therein are contained in the sub-filter 2.
The collected particulates are deposited on the sub-filter 2. At the same time when the main filter 1 is regenerated, the detection filter 25 is energized and the detection filter 2 is also energized.
5 may be reproduced at the same time, but may be executed in step 52 following the reproduction of the sub-filter 2. In the regeneration processing of the detection filter 25, the processing is repeated until the resistance value R _X of the detection filter 25 becomes larger than the initial resistance value R ₀ , and the detection filter 25 is regenerated (step 53). Alternatively, as shown in FIG. 4, the wire mesh 3 made of heat-resistant steel capable of supplying electricity to the surface of the detection filter 25.
4 is arranged, even if the wire material forming the wire mesh 34 is partially cut between the terminals 26, carbon is deposited on the cut portion of the wire material and the resistance value of the wire mesh 34 becomes small. Therefore, the wire mesh 34 is energized to detect the filter 25.
Screening or regeneration of.

When the regeneration of the main filter 1 is completed, the controller 10 operates the actuator 36 to activate the on-off valve 5.
To open the main exhaust gas passage 12 (step 4
Along with 9), the actuator 11 is operated to issue a command to close the bypass passage 14 by the bypass valve 9 (step 50). When the opening / closing valve 5 is opened and the bypass valve 9 is closed, the exhaust gas passes through the exhaust gas passage 22 through the main filter 1, and the normal exhaust gas processing, that is, the particulate collection processing by the main filter 1 is performed. become. At this time, a small amount of exhaust gas is sent to the bypass passage 14 through a through hole or a gap formed in the bypass valve 9. Therefore, the heater provided in the sub-filter 2 is energized, and the particulates collected in the sub-filter 2 are incinerated by using the air contained in a small amount of exhaust gas passing through the sub-filter 2 from the bypass passage 14. , Sub-filter 2
Is reproduced (step 51). In this diesel particulate filter, the above-mentioned operation cycle is repeated and exhaust gas is continuously purified.

[0031]

The control device for the diesel particulate filter according to the present invention is configured as described above and has the following effects. That is, the control device for this diesel particulate filter is provided with a main filter and a sub-filter arranged in the exhaust gas passage of the diesel engine, and the main exhaust gas passage is opened / closed by the bypass valve and the bypass passage is opened / closed by the controller. In response to a detection signal from a particulate deposition sensor and a temperature sensor equipped with a detection filter, the heating heater disposed on the surface of the main filter is energized to control the heating and incineration of the particulate, so the particulate The accumulation amount of the particulate matter collected by the filter can be accurately detected by the accumulation sensor, and the particulate matter can be heated and incinerated in a timely manner according to the accumulation amount. Moreover, since the particulates are heated and incinerated regardless of the operating state of the engine, the main filter can be regenerated in a short time and less electric energy is required. Further, the regeneration timing of the main filter can be set at the optimum timing, the frequency of use of the main filter can be increased, and the exhaust gas can be purified optimally. In addition, since the regeneration timing of the main filter can be controlled regardless of the operating state of the engine, it is possible to reliably heat and incinerate the particulates in any operating state of the engine, and eliminate the need for sensors for detecting the engine rotation and load. Become.

The amount of particulate matter deposited on the detection filter can be directly detected by its resistance value, and therefore the amount of particulate matter trapped on the filter body can be detected. The amount of deposition on the filter body can be detected accurately and quickly, and the time of regeneration of the filter body can be controlled accurately. If the detection filter is also regenerated at the same time when the filter body is regenerated, exhaust gas purification can be repeated.

As described above, this diesel particulate filter device can directly measure the amount of particulates deposited on the filter body by using the particulate deposit sensor, so that the exhaust gas pressure fluctuates depending on the engine load and engine speed. However, the amount of particulates deposited on the filter body can always be detected accurately, and the durability of the filter body can be improved without erroneous regeneration time of the filter body. Moreover, since this diesel particulate filter device has the above-mentioned configuration, the device itself can be formed into a compact and simple structure, and the function of treating exhaust gas discharged from the diesel engine is extremely simple and continuous. Thus, the exhaust gas can be purified, and for example, it can be mounted satisfactorily in a severe place due to the space of a vehicle or the like.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a diesel particulate filter device according to the present invention.

FIG. 2 is a plan view showing an embodiment of the particulate deposition sensor of FIG.

FIG. 3 is a sectional view showing another embodiment of the particulate deposition sensor of FIG.

4 is a plan view showing another embodiment of the particulate deposition sensor of FIG. 1. FIG.

FIG. 5 is an enlarged cross-sectional view showing a wire member of a wire mesh that constitutes a heater of the diesel particulate filter device of FIG.

FIG. 6 is a process flow chart showing an operation of the control device of the diesel particulate filter.

7 is a graph showing the relationship between engine speed and load, and exhaust gas pressure for the filter body of FIG.

[Explanation of symbols]

 1 Main Filter 2 Sub Filter 3 Filter Body 4 Bypass Cylindrical Body 5 Open / close Valve 6,7,34 Wire Mesh 8 Particulate Deposit Sensor 9 Bypass Valve 10 Controller 12 Main Exhaust Gas Passage 11,36 Actuator 14 Bypass Passage 22 Exhaust Gas Passage 25 Detection Filter 29 Temperature sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F01N 3/02 ZAB 321 K

Claims (5)

[Claims] 1. A control device for a diesel particulate filter installed in an exhaust gas passage of a diesel engine, comprising a main filter having a large collection capacity of particulates and a sub-filter having a small collection capacity, the main filter and the Each valve that opens and closes a passage with the sub-filter, a heater for incinerating the particulates collected in the main filter and the sub-filter,
A particulate deposition sensor that detects the amount of particulates deposited on the main filter, and a controller that controls the valves and the heater in response to a detection signal of the particulate deposition sensor. Control device for diesel particulate filter. 2. A main filter arranged in an exhaust gas passage of a diesel engine, a sub-filter arranged in a bypass passage in the main filter, an opening / closing valve opening / closing the main exhaust gas passage, a bypass valve opening / closing the bypass passage, A particulate deposition sensor equipped with a heater arranged on the surface of the main filter, a heater arranged on the surface of the sub-filter, and a detection filter installed in the exhaust gas passage on the exhaust gas upstream side of the filter body. A temperature sensor for detecting the temperature of the main filter, and a heating / closing valve, the bypass valve, and the bypass valve in response to detection signals from the particulate deposition sensor and the temperature sensor for heating and incinerating the collected particulates. A diesel characterized by comprising a controller for controlling the heater. Control device for particulate filter. 3. The particulate deposition sensor has a detection filter having substantially the same ventilation resistance per unit volume as the main filter, terminals made of conductive metal attached to both ends of the detection filter, and resistance between the terminals. The control device for the diesel particulate filter according to claim 2, wherein the control device comprises a resistance detector that measures a value. 4. When the temperature of the main filter is high,
The diesel particulate filter control device according to claim 2 or 3, wherein regeneration of the main filter is started even in a state where the particulate deposition amount of the particulate deposition sensor is equal to or less than a predetermined amount. 5. When the temperature of the main filter is low,
The control device for the diesel particulate filter according to claim 2 or 3, wherein the regeneration of the main filter is started only when the particulate deposition amount of the particulate deposition sensor becomes a predetermined amount or more.